Here is a great little gallery of some of Syd Mead's works, scanned in high resolution. Most of the paintings are old pieces of his, so they were created traditionally using gouache paints.

Syd Mead was a bit of an 'acquired taste' for me, and it took longer than I'd like to admit to catch on to just how talented this man is. So take a look, take your time, and if you like what you see, consider getting one of his many fantastic art books.